Production of omega-substituted monocarboxylic acids



United States Patent PRODUCTION OF w-SUBSTITUTED CARBOXYLIC ACIDS Joe B. Lavigne, Berkeley, Calif., assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware No Drawing. Filed Feb. 12, 1958, Ser. No. 714,682 Claims. (Cl. 260-408) MONO- where R is a substituted or unsubstituted divalent radical containing from 3 to 9 carbon atoms in the ring containing the carbon atom of the carbonyl group, with a redox reducing agent. The patent describes a number of cyclic ketones which may be reacted with hydrogen peroxide to form peroxides which yield dibasic carboxylic acids when treated with redox reducing agents. As pointed out by Roedel, the cyclic ketone used may be, for example, one of the following:

Cyclobutanone, where R: (CH 3 Cyclopentanone, where R= (CH Cyclohexanone, where R= (CH Cycloheptanone, where R= (CH Cyclooctanone, where R: (CH Cyclononanone, where R= (CH Cyclodecanone, where R: (CH

Alternatively, R may contain various substituents, or may contain one or more nonaromatic double bonds. A number of redox reducing agents suitable for use in the reaction are described, and the nature of the reactered, and the primary product is not a dibasic carboxylic acid but an w-halosubstituted aliphatic monocarboxylic acid having the same number of carbon atoms as are ponent of the reaction mixture.

All oxidizing agents are contemplated as operative in the process; however, in order that the reducing agent will not be consumed by the oxidizing agent, it is desirable that the oxidizing agent be sufiiciently weak that the reducing agent will react with the hydrocarbon peroxide more rapidly than it will react with the oxidizing agent. It has been found most desirable to employ an oxidizing agent comprising a salt of a variable valent metal. It is advantageous to use oxidizing and reducing and desirably substantially less,

dition,

examples.

Water-washed and then combined, dried,

cyclohexanone are recovered in the distillate.

7o liliters, 2.1 mols) were added.

agents having cations of the same metal since additional reducing agent can then be generated from the oxidizing agent.

Suitable reducing agents are the heavy, variable valent metals, as well as l-ascorbic acid, sodium bisulfite, the reducing sugars, and the other reducing agents common to the redox art.

10 above reducing agents with the oxidizing agent.

The concentration of the reducing agent should be less, than the concentration of the oxidizing agent; that is, the mol ratio of the oxidizing agent to the reducing agent should be at least one and preferably between 2 and 20.

g The halogen ion may be introduced into the reaction 20 mixture in the form of the free acid, such as hydrochloric 30 the range of about C. to C., and preferably from about l5 C. to +15 C. Pressures which are higher or lower than atmospheric may be employed.

The process and advantagesof the present invention will be illustrated further by. reference to the following Example 1 Hydrogen peroxide (56.7 grams, 0.5 mol) is addedto cyclohexanone (198 grams, 2.0 mols) during a period 40 of 7 minutes. The temperature rises from atmospheric 5 During the addition, the temperature is maintained at -15 C. Concentrated hydrochloric acid (87.5 milliliters, 1.05 mols) and 750 milliliters of water are added to the reaction product mixture. The solution is extracted with benzene and the benzene solutions are ture of 110 C. The distillation residue contains 57.4 grams of w-chlorocaproic acid. 149 grams of unreacted ydrogen peroxide conversion is 100%. The yield of w-chlorocaproic acid is 81.6% based on hydrogen peroxide and 84.5% based on cyclohexanone converted. Hydrogen peroxide (30%, 113 grams, 1.0 mol) was Example 2 added to cyclohexanone (392 grams, 4.0 mols) over 12 minutes. The temperature rose to 41 C Methanol 65 13 minutes into methanol (400 milliliters) containing ferrous cholride tetra-hydrate (20.0 grams, 0.10 mol). The temperature was maintained near .-5 C. Water (1000 milliliters) and concentrated hydrochloric acid milg The solution was ex-. tracted with benzene (3x400 milliliters), andthe extracts were washed, combined, dried and distilledto a pot teary Patented May 31,

. 7 3 perature of' 110"C. at' 2 millimeters pressure. The distillate contained" 274 grams of cyclohexanone for a 30% The pot residue contained 125 grams of toacid and 7.6 grams of methyl w-ChlOl'O- theory based on conversion. chlorocaproic caproate, for a total yield of 88% of hydrogen peroxide.

Example 3 Actual Theoretical Example 4 Hydrogen peroxide (30%, 56.7 grams, 0.5 mol) was added, to cyc1opentanone(420.6 grams, 5.0 mols) at room temperature. The, solution was heated to 4?. C. and then allowed to cool, It was then added during 5 min! utes to a, methanol (150 milliliters) solution of ferric chloride hexahydrate (270.3 grams, 1.0 mol) and ferrous chloride tetrahydrate. (9.9 grams, 0.05 mol). The temperature was maintained at C. during the reaction, and nitrogen was bubbled through continuously. Water (3 liters) and concentrated hydrochloric acid (46 milliliters) were added. The solution was extracted with four portions of benzene, and the extracts were washed, combined, dried, and distilled to give w-chlorovaleric acid. The chloroacid boils at l18-12 0 C. at 5 millimeters.

Example 5 Cyclohexanone hydroperoxide in cyclohexanone was prepared as usual from the ketone (196 grams, 2.0 mols) and 30% hydrogen peroxide (56.5 grams, 0.5 mol). It was then added at C. to +5 C. to a methanol solution prepared from ferric bromide hydrate (323 grams)and ferrous sulfate heptahydrate (13.9 grams). The reaction was treated with water (500 milliliters) and concentrated hydrochloric acid (175 milliliters). Extraction with benzene (3 X200 milliliters) was followed by the usual work up to give an 86% yield of w-bromocaproie acid and 219% yield of methyl w-bromocaproate. The bromoacid boils at l2 5-130 C. at 5 millimeters pressure.

* Example 6 Cyclohexanone hydropeoxide was prepared by adding hydrogen peroxide (113 grams, 1.0 mol) to cyclohexanone (392 grams, 4.0 mols). The temperature rose to 41 C. Methanol milliliters) was added and the solution added during 14 minutesto methanol (400 milliliters) containing cupric chloride dihydrate (341 grams, 2.0 mols) and cuprous chloride (9.9 grams, 0.1 mol). The temperature was maintained between -3 and -11 C. A nitrogen ,tmosphere was maintained. Water (lliter) and concentrated H61 (175 milliliters) were added and the solution fxtracted with benzene (3 x400 milliliters) and the extracts treated as usual. A 40% yield .of w-ChlOIOCaPI'OlC acid and a 15% yield of methyl w-chlorocaproate based on hydrogen peroxide were obtained.

Example 7 The above experiment was repeated using 2 mols chrornic chloride hydrate and 0.1 mol of chromous chloride in methanol. The reaction solution was worked up as usual with dilute acid and benzene extraction to give w-ChlOIOCflPIOlC acid and methyl-w chl0rocapro ate.

The foregoing examples have referred specifically to the use of iron, copper and chromium salts as oxidizing and reducing agents to produce the desired halosubstituted aliphatic acids. The corresponding salts of other metals which exhibit at least two valence levels, for example, tin, nickel, cobalt and manganese, may also be employed to produce the desired substituted aliphatic acids, and the specific metal salts used as oxidizing and reducing agents need not be salts of the same metal.

For instance, a suitable combination of oxidizing and reducing agents may be acupric salt used as the oxidizing agent and a ferrous salt used as the'reducing agent.

As indicated by Example 3, protracted reaction periods in the presence of an alcohol solvent may result in the production of the corresponding alkyl ester of-the w-haloacid. The formation of the ester during the reaction, rather than the free acid, permits its ready isolation from the reaction mixture without interference because of the formation of metal salts of the carboxylic acid. The ester is a valuable chemical intermediate, for example, in the preparation of certain linear polymers, and it may be substituted for fatty esters in essentially. all the uses of these latter materials.

The w-haloaliphatic acids produced pursuant to this invention are highly useful materials. They may be substituted for fatty acids in essentially all the usesof these, lattermaterials. The w-chlorocaproic acids, for example, can be converted to o-cyano acids by heating strongly with potassium or sodium cyanide. The resulting w-cyano acids are then readily reduced to produce the w-amino acids. The w-halo acids can also be dehydrohalogenated, yielding unsaturated aliphatic monocarboxylic acids, which may be converted to esters having good drying properties.

While this invention has been directed to the production of (ii-substituted carboxylic acids from hydroperoxides derived, for instance, from cyclic ketones of the formula: r

of the tertiary hydroperoxides de: from alkyl alicyclic alcohols of the a similar treatment rived, for instance, general formula:

%! C;-QH

will give iii-substituted ketones. Similarly, alkyletherde: rivatives of the cyclic peroxides may be used in the invention instead of cyclic peroxides to produce ti-substi-v tuted acid esters instead of w-SllbStitlltGd acids.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A process for producing wahaloaliphatic monocare boxylic acids which comprises treating a peroxide compound having a cyclic structure consisting .of from 4 to 10 carbon atoms in the primary ring, saidperoxide being obtainable by reacting together hydrogen peroxide and a cyclic compound .of the formula:

(pl where R is an alkylene group containing from 3 to 9 carbon atoms in the alkylene chain, with 0.1 to 20 molar equivalents of an oxidizing agent comprising a variable valcnt metal in the presence of a redox reducing agent and a halogen ion selected from the group consisting of chlorine and bromine ions, and separating an -haloaliphatic acid from the reaction mixture.

process for producing w-haloaliphatic monocartreating a peroxide comwhere R is an alkylene group containing from 3 to 9 carbon atoms in the alkylene chain, with about 0.1 to

to said reducing agent being between rating an w-haloaliphatic monocarboxylic acid from the reaction mixture.

4. The process of claim 3 in which the metals of said oxidizing agent and reducing agent are the same.

The process of claim 3 in which said oxidizing agent is a ferric halide and said reducing agent is a ferrous salt.

6. The process of claim 3 is a cupric halide and said salt.

7. The process of claim 3 in which said oxidizing agent is a chromic halide and said reducing agent is a chroinous salt.

8. The process of claim 3 in which said oxidizing agent is ferric bromide.

9. A process for producing w-chloroaliphatic monocarboxylic acids which comprises treating a peroxide compound having a cyclic structure consisting of from 4 to 10 carbon atoms in the primary ring, said peroxide being obtainable by reacting together hydrogen peroxide and a cyclic compound of the formula:

R where R is an alkylene group containing from 3 to 9 carbon atoms in the alkylene chain, with a ferrous ion as the redox reducing agent in the presence of 0.5 to 5 mols of ferric chloride per mol of peroxide, and separating an w-chlorocarboxylic acid from the reaction mixture.

10. The process of claim 3 characterized further in that said process is conducted in the presence of at least one mol of a lower alkanol per w-haloaliphatic monocarboxylic in which said oxidizing agent reducing agent is a cuprous References Cited in the file of this patent UNITED STATES PATENTS 2,828,338 Lavigne Mar. 25, 1958 

1. A PROCESS FOR PRODUCING W-HALOALIPHATIC MONOCARBOXYLIC ACIDS WHICH COMPRISES TREATING A PEROXIDE COMPOUND HAVING A CYLIC STRUCTURE CONSISTING OF FROM 4 TO 10 CARBON ATOMS IN THE PRIMARY RING, SAID PEROXIDE BEING OBTAINABLE BY REACTING TOGETHER HYDROGEN PEROXIDE AND A CYCLIC COMPOUND OF THE FORMULA: 